Clinical and radiographic feature of pulmonary nocardiosis: A study of 102 cases

BACKGROUND Nocardia pneumonia is an infection that occurs in patients with underlying diseases. Previously, due to limited detection methods, its detection rate and typing posed significant challenges. However, with advancements in detection techniques, the detection rate has significantly increased, and different Nocardia species exhibit distinct imaging characteristics. AIM To retrospectively analyze the etiological and imaging features of pulmonary Nocardia pneumonia and to examine the differences in chest imaging manifestations among different Nocardia species. METHODS The medical records of 102 patients with pulmonary nocardiosis who were admitted to Beijing Chaoyang Hospital from January 2017 to December 2024 were collected. Data including name, gender, underlying comorbidities, etiological characteristics, diagnostic methods, chest computed tomography features, and therapeutic agents were recorded. RESULTS Among the 102 patients, 55 were male and 47 were female, with a median age of 61 years. Bronchiectasis was the most common comorbidity, observed in 54 patients (52.9%). Sixty percent were diagnosed using metagenomic next-generation sequencing. Nocardia gelsenkin was the most prevalent Nocardia specie, while Aspergillus and Pseudomonas aeruginosa were identified as the predominant co-pathogens in these pulmonary nocardiosis cases. Pneumonia caused by Nocardia wallacei primarily presented with bronchopneumonia as the main imaging feature, while other Nocardia species more commonly manifested as consolidation, often accompanied by nodules, cavities, and pleural effusion. The imaging features in immunosuppressed patients were more diverse, with frequent coexistence of multiple patterns. CONCLUSION Nocardia pneumonia commonly coexists with bronchiectasis. While metagenomic next-generation sequencing has greatly enhanced its detection rate, Nocardia wallacei pneumonia is distinguished on chest computed tomography by its primary presentation of bronchopneumonia, unlike other types.